Background:Encephalomyocarditis
virus (EMCV), a member of the genus Cardiovirus in the Picornaviridae
family , is regarded as a virus of rodents but can on occasion
cause disease in a wide variety of animals, including domesticated
pigs. EMCV may either cause sudden death in piglets or reproductive
failure in sows. These disease syndromes were first observed in
Europe in 1986 and have increased in frequency since that time.
The transmission and spread of this emerging European disease
is poorly understood both in wildlife and domesticated species.

1)
Firstly, the epidemiology and economic implications of EMCV
infection in pigs will be studied by investigating the mode
and kinetics of virus spread on an infected farm. The prevalence
and spread of EMCV throughout Europe will be studied by the
collection and genetic analysis of viruses from both wildlife
(rodents etc.) and pigs, and by surveying these populations
for antibodies to EMCV. The route of EMCV transmission will
be studied experimentally. Host (genetic) and environmental
factors (such as stress) which may influence the outcome of
an outbreak will be studied. We will determine reliable parameters
of immune protection. All the above data will be used to create
an epidemiologic and economic computer model for EMCV disease
which may also be used for emerging diseases in general.

2)
Virus strain virulence. We will investigate the basis for the
variable virulence of EMCV strains in pigs by characterisation
of viruses at the genome level. Initially genome areas known
to be involved in the virulence of other Picornaviruses (S'
UTR, poly-C tract, VP1, 3' UTR) will be studied in a number
of well-characterised EMCV strains which cause either myocardial
or reproductive disorders. Additionally, a molecularly-cloned
infectious cDNA will be constructed to investigate virulence
by the creation of chimeric viruses or by reverse genetics.
The implications for the emergence of disease due to the quasispecies
nature of EMCV will also be investigated and can be useful for
the study of other emerging RNA-viruses.

3)
Diagnosis. Molecular diagnostic assays previously developed
by us under an AIR project will be updated to allow an immediate
appraisal of the impact of EMCV infection on the status of animal
health.

This
will include further optimisation of all stages of diagnostic
PCRs and the application and development of new assays e.g. antigen-capture
PCR. If possible, diagnostic tests based on molecular markers
of virulence will be developed. Additionally, comparative evaluation
of these assays will be undertaken by all participants. It is
envisaged that these studies will make an important contribution
to the understanding of the epidemiology and future control of
this emerging pig disease.